Interesting question,
Does the duty time issue become relevant if you are a pilot and have a second paid job?
i.e . Pilot and Barman
or Pilot and Bus driver
or Pilot and Cook
Hypothetically are you bound by duty time restrictions if you are a Pilot
and pour a few beers at the local Rotary Club picnic
or are a volunteer driver of the Council Community Bus
or help out at the local fundraising sausage sizzle
Where is the line drawn?
Surely it is fitness to do the job. Having a second job probably maintains a better level of fitness than spending your spare time as a Norm (or Norma) emptying a few cold ones whilst perched on the couch vegetating in front of the TV
BTW, unless you crack a regional or better you may need that second job if you have a wife, 3 kids, dog and bank manager to support !!